Field of the Invention
The present disclosure relates to the field of power supply, and in particular, to a control circuit and a control method for a power converter.
Description of the Related Art
Power converters are widely required to provide a constant current in many applications, for example, in LED lighting field, a constant current is used to drive an LED lamp to maintain its luminous intensity. In a conventional control method, a compensation signal is obtained by calculating an error between the feedback signal of the output current and a reference signal, the compensation signal is used to control the on time period or control the peak value of the inductor current flowing through the inductor in the power switch, thus achieving a current closed-loop control so that a constant current control is obtained.
In the above control method, a compensation capacitor must be introduced in the feedback loop to obtain a stable compensation signal because the ripple of the current is large. However, the compensation capacitor increases the size and cost of the power converter, which is disadvantageous for the circuit integration of the power converter. When the main circuits of the power converter except the compensation capacitor are integrated into a chip, extra pins are required for connecting to the compensation capacitor located outside the chip.
Thus, it is desired to further simplify the control circuit of the power converter in order to reduce the chip size and the number of the peripheral components.